Investigators said the scene was likely caused by two six-liter pressure cookers just like the ones many people have in their homes.

Dr. Van Romero, vice president of Research at NM Tech, said the deadly explosion came from the same science used to speed up cooking. The pressure builds until it bursts, but in this case, the cookers were filled with metal, ball bearings and nails.

Romero said it wouldn’t take much to create the blast.

“You can get that much pressure from a half pound of explosives,” Romero said.

Scientists at NM Tech have been studying video of the scene. They are generally called to partner with the FBI to re-create explosions after major attacks. Romero confirms he has been in contact with the Department of Homeland Security.

According to Romero, the devices appear to have been placed low to the ground so the shrapnel could blast at just the right height to inflict the most possible harm.